Here is how a B205 actually gets ordered. You find the drawing below and print it. You crawl into the compartment with a tape and figure out where the fill hose can actually make its bend, where a vent can climb without a trap, where the pickup lands at the low corner once the boat sits on her lines.
What arrives is a 20 gallon marine fresh water tank in rotomolded FDA-compliant polyethylene: one seamless piece, potable-rated, nothing to corrode and no fabricated joints to weep. It ships at 83 lb, and in service it carries about 167 lb of water at 8.34 lb per gallon - so bear it flat and strap it to structure, same as any tank worth keeping.
This made-to-order workflow is not a boutique upsell; it is simply how Ronco has run its Tustin, California shop since 1974. The catalog holds a crowd of 20 gallon marine shapes precisely because hulls disagree about what a 20 gallon space looks like - this is one answer among several.
If the outline is close but not right, the boat tank category has the siblings, and the Ronco Plastics hub has everything else. One Source Plastics is an authorized Ronco Plastics dealer.
Fittings
This tank has a molded shape (see the drawing), so it is sold as a blank tank with no fittings installed. Add the Ronco 3-inch uniseal (F3UNISEAL), a loose pipe-to-tank seal you install yourself, if you need a sealed pipe connection.
Technical drawing: download the Ronco Plastics B205 dimensional drawing - print it to plan your install. Sold blank, with no fittings installed.
